1. Field of the Invention
The present invention relates to an electronic device of a system for simultaneously operating a plurality of electronic devices, a power source control method, a radio over fiber (ROF) system and its power supplying method and a remote unit.
2. Description of the Related Art
For instance, when starting up electronic devices and information processing terminals such as a plurality of automatic teller machines connected to a host device in an automatic teller system of a bank, inrush currents are greatly generated when power is turned on. And also when television receivers of a video distribution system, etc., are turned on simultaneously, rush currents are greatly generated. Therefore, it is needed for the power source capacity of the system to be made larger than that of in the normal operation. And an occurrence of variations in power also at a primary power source side results in prevention of a stable operation.
As a measure to deal with foregoing problems, a conventional system starts up each electronic device in turn by shifting power supply timings (start up timings) little by little to each electronic device on the power supply side of the system then the system suppresses addition and superposition of the rush currents. For the method of the measure, the video distribution system employs a method for inserting a delay line in the middle of a bus line of a power source supplying power to the television receiver [for instance, Jpn. Pat. Appln. KOKAI publication No. 2-295389 (on page 4, FIG. 1)].
In an ROF system, a remote unit power supply device disposed on a base station side of a cellular phone supplies power to each remote unit. Each remote unit having been installed in a distant construction such as a building or a tower, feeder cables are not connected through bus lines but laid to each remote unit from the remote unit power supply device in a radial pattern. Accordingly, it is impossible to easily set a delay time only by inserting delay lines each having the same delay time into the bus line of a remote unit to be connected next in cascade between adjacent stations. Therefore, it is needed to manage complicatedly in such a manner that delay lines deferring in value for each remote unit have to be inserted to feeder lines for each remote unit.
In a conventional method, the ROF system has to manage the remote unit power supply device so as to supply power with delay times deferring for each electronic device and television receiver from the power supplying device side after power is turned on. Therefore, the ROF system has a problem that a complicated management is required and a device scale is increased.